Transmitter with a remote unit in an electric net data transmission system

ABSTRACT

A transmitter for sending a data transmission signal to an f electric net, whereby the apparatus comprises signal-shaping and adjustment devices ( 3 ) and connecting devices ( 50 ) including necessary accessories for connection to the electric net, signal amplifiers ( 20 ) and a connecting cable between the transmitter and the connecting point of the electric net, as for instance 230 V, 50 Hz phase rail (L) and zero rail (N) or a wall outlet as connecting points. The apparatus is divided into two or several parts, at least a first part ( 3 ) and a second part (TX/REMU), whereby second part (TX/REMU) includes at least connecting a unit ( 50 ) for connection to the electric net and a connecting cable and for connecting said second part to the electric net, whereby the length (L W ) of connecting cable is under 5 m.

The invention is suited for use in electric nets i.e., electricalnetworks, for instance 12 VAC/DC, 24 VAC/DC, 48 VAC/DC, 115 VAC, 400VAC, to prevent the level from getting lower of a signal, sent by atransmitter of a data transmitting system in a said net, with smallvalues of load impedance Z_(LOAD) (in voltage rail) and with greatvalues of the equivalent series impedance Z_(W) of the electric netcable (long connecting cable to electric net, that is the datatransmission distance). By means of a method as per the invention andthe structure of the transmitter it is possible to keep the signalU_(LOAD) sent by the transmitter large enough in the voltage rail of theload impedance Z_(LOAD) even if there were from the transmittingapparatus to the electric net voltage rail a distance of tens of or evenover hundred meters. Without the method reliable operation under aboveconditions would be occasionally impossible, because of a too lowtransmission signal.

Generally in traditional solutions there are two problems:

-   1) The level of transmission signal gets strongly lower, when the    net impedance is quite low.-   2) For instance, in transmitting situation no signal high enough can    be achieved between 230 V 50 Hz phase and zero rail (L-N) of the    electric net, since energy consuming apparatuses cause on the signal    frequency a quite a strong load, i.e. low load impedance Z_(LOAD).    This is influenced by the fact that there is from the transmitting    apparatus a long cable connection (the equivalent series impedance    Z_(W) of the cable is high on signal frequency) to above phase and    zero rail. According to the principle of voltage distribution the    U_(LOAD) is then low, i.e. the situation is bad. FIG. 1 shows the    attenuation impact of the cable in a traditional solution, when the    Z_(LOAD)=1 ohm.

In the more developed modern techniques the problem presented in pos. 1)is already solved so that the outgoing signal of the transmitter remainsalmost constant, i.e. independent of the net impedance. However, itdoesn't be of any help on resolving the problem of pos. 2), because ofthe series impedance Z_(W) of the connecting cable of the apparatusand/or the cable and of the low load impedance Z_(LOAD) between phaseand zero rail in the electric net. There is a surprisingly good solutionto the problem in this invention, where the impact of attenuation on thesignal of the series impedance Z_(W) of the connecting cable iseliminated almost completely.

FIG. 2 shows the impact of attenuation the cable in the invention, whenthe Z_(LOAD) is 1 ohm.

In transmitting situation it is decisive that for instance the “railsignal” U_(LOAD) of the fuse box of an apartment, which is the signalvoltage between phase rail L and zero rail N in fuse box U_(L-N), is ashigh as possible even with low Z_(LOAD) values of the load impedance.

The apparatus as per the invention is characterized in that theequipment is divided into two or several parts, at least in a first part(3) and a second part (TX/REMU), whereby the second part (TX/REMU)includes at least a connecting unit (50) for connection to the electricnet and a connecting cable for connection of said part to the electricnet, whereby the length L_(W) of the connecting cable is under 5 meters.

The invention is based on that an apparatus operating in the electricnet is in a way divided into two parts, of which the first partcomprises most suitably the equipment to form and adjust the signal 31and the second part comprises a transmitter a remote unit, hereaftercalled TX/REMU. The transmitter remote unit TX/REMU is placed as closeas possible to the wall outlet of an electric net 230 V, 50 Hz or to aphase and zero rail for instance in a fuse box. The length of theconnecting cable is held as small as possible, e.g. L_(W) is under 5meters or more suitably under 3 meters or even under 1 meter, as shownin FIG. 4. Possibly the transmitter remote unit TX/REMU can be placed inthe voltage rail or even plugged in a wall outlet, if regulations allow.Then there is no connecting cable and the L_(W) is 0 meter. The firstpart of the apparatus can be placed even far from the remote unit, thedistance can be tens or even hundreds of meters.

The invention is disclosed with reference to the enclosed drawingfigures, where

FIG. 1 shows the attenuation impact of the cable in a traditionalsolution, when the Z_(LOAD) is 1 ohm.

FIG. 2 shows the attenuation impact of the cable in the invention, whenthe Z_(LOAD) is 1 ohm.

FIG. 3 shows a simple application of the invention.

FIG. 4 shows an effective application of the invention.

The transmitter remote unit TX/REMU gets the steering of its operationover the signal cable from the first part of the bipartitionedapparatus. The length L_(S) of the signal cable can be tens and evenhundreds of meters and has no impact on the size of the “rail signal”U_(LOAD), which is to be transmitted to the electric net. Refer FIGS. 2and 4. The first part 3 and second part TX/REMU can be connected alsowirelessly with an optical fibre cable or otherwise.

The transmitter remote unit TX/REMU is located for instance in a livingroom or in the main electric center, (e.g., switchboard) just beside thefuse box (fuses and phase rail and zero rail and switch) or inconnection with it in its own box or in a wall outlet or near it. Acable comes to it from the fuse box rails over the fuse or from the walloutlet and, in addition, the signal cable from the first part of theapparatus, where generally the operation lights and switches arelocated.

The transmitter remote unit TX/REMU contains for instance a signalamplifier 20 (e.g. 95-125 kHz) low pass filter or band pass filter 40,but in any, case it contains a field unit connecting unit 50 forconnection to the electric net. In addition, the remote unit TX/REMU cancontain many other operation blocks and functions. It can also have amains transformer and a voltage regulator.

The first part 3 of the apparatus can for instance in an apartment beplaced in the signal cable end, even in a living room. Generally itincludes the signal lights and control devices 32 such as operatingswitches and other operating switches and other operation means of theapparatus.

FIG. 3 shows a simple application of the invention and FIG. 4 a moreefficient application of the invention.

The second part, remote unit TX/REMU, of the transmitter must be as toits mechanics as small as possible and suitably shaped, so that it couldbe utilized appropriately in the main electric centre of an apartmenthouse or in the kWh-meter closet, for instance. There is not often muchplace available. The connecting cable taken to the phase and zero railL, N or to a wall outlet must be as short as possible (e.g. L_(W)=under1 m). Regulations restricting the assembly must be taken intoconsideration.

1. A transmitter apparatus for sending a data transmission signal overpower lines of an electrical power network, wherein the transmitterapparatus comprises control devices, signal-shaping and adjustmentdevices, and connecting devices for connection to the electricalnetwork, including a signal amplifier, and a connecting cable betweenthe transmitter apparatus and a connecting point of the electrical powernetwork, wherein the improvement comprises: wherein the transmitterapparatus for sending the data transmission signal over power lines ofthe electrical power network is divided and physically separated into atleast a first part and a second part connected by one of a signal cable,an optical fiber, and a wireless connection, said first part includingat least the control devices, one of said first and second partincluding the signal shaping and adjustment devices for generating thedata transmission signal, said second part including at least aconnecting unit for coupling the data transmission signal to theelectrical power network, and the connecting cable connecting saidsecond part at least near to phase and zero rails or to a wall outlet ofthe electrical power network; wherein the first part steers operation ofthe second part over the one of the signal cable, the optical fiber, andthe wireless connection; and wherein the length of the connecting cableis under 5 m.
 2. A transmitter apparatus according to claim 1 whereinthe length of the connecting cable is under 1 m when the second part isconnected to the phase and zero rails or to the wall outlet of theelectrical network.
 3. A transmitter apparatus according to claim 1wherein the connecting cable can be connected to voltage rails in adirect-current electrical power line or an alternating-currentelectrical power line or to another connection point of an electricalpower line.
 4. A transmitter apparatus according to claim 1 wherein theconnecting cable can be connected to 3-phase rails or to a 3-phaseoutlet or to another connection point of a network cable.